Process for separation and recovery of carbon monoxide

ABSTRACT

A process for the separation of carbon monoxide from mixed gases comprising contacting the mixed gases with an absorbent system consisting essentially of an inert diluent and a copper (I) salt of a sulfonic acid or of a dialkyl phosphate.

This is a division of application Ser. No. 618,721, filed Oct. 1, 1975,now U.S. Pat. No. 4,042,669.

This invention relates to the separation of carbon monoxide from a gasmixture. In one aspect the present invention relates to a novel carbonmonoxide absorbent. In another aspect the present invention relates tothe preparation of a carbon monoxide absorbent. In yet another aspectthe present invention relates to a process for the separation of carbonmonoxide from a gas mixture.

A variety of processes are known for the separation of carbon monoxidefrom gas mixtures. On the one hand, carbon monoxide is an undesirablecomponent of some mixtures and must be removed. On the other hand,carbon monoxide is a potentially versatile intermediate for preparing avariety of clean burning fuels and large volume chemicals. Complexcompounds of univalent copper and possibly other heavy metals suitablefor forming complexes have been used for separating carbon monoxide. Forthis purpose, for instance, cuprous oxide, cuprous chloride, cuprousnitrate, cuprous carbonate, cuprous lactate, cuprous formate, or theunivalent copper salts of other inorganic or organic carboxylic acids,are dissolved or suspended in aqueous solutions of the respective acidsor water soluble salts of the same. Thus, for instance, cuprous chlorideis dissolved in aqueous solutions of sodium chloride, calcium chloride,magnesium chloride, and the like, or in mixtures of such salts. Theabsorption of carbon monoxide in such absorption means is effected bywashing the gas mixtures containing carbon monoxide in a known manner inabsorption towers containing filling material, shower washers, and thelike, at normal or increased pressure, and counterflow or uniflow or bybubbling the gas through the absorption means. These absorption meanscombine with carbon monoxide to form more or less unstable cuprouscarbon monoxide complexes. The absorption means laden with carbonmonoxide release the carbon monoxide in the form of gas, when heated,and/or when the pressure is reduced. Thus, the carbon monoxide can berecovered and the absorption means can be regenerated to be reused forabsorption.

The cuprous ion has long been recognized as one of the few agents whichcomplexes reversibly with carbon monoxide. Aqueous solutions of certaincuprous complexes have formed the basis of commercial carbon monoxideremoval systems. However, these complexes are usually unstable, andrequire the continuous addition of reagents to maintain theircomposition and to maintain their absorptive capacity constant. Also,many of them are corrosive, requiring special materials of construction.

The absorptive capacity for carbon monoxide of many of these cuprouscompounds is strongly influenced by temperature across the entire usabletemperature range. Certain of the processes employing these cuprouscompounds require, for example, that the absorptive step be carried outat a relatively low temperature and that the desorption step be carriedout at a relatively high temperature. Thus, the energy requirement forseparating carbon monoxide from gas mixtures by such processes can beexcessive.

It is an object of this invention to provide a carbon monoxide absorbentcomposition.

It is another object of this invention to provide a process for thepreparation of a carbon monoxide absorbent composition.

It is yet another object of this invention to provide an improvedprocess for separating carbon monoxide from a gas mixture.

Other objects, aspects and advantages of the present invention will beapparent from the specification, appended claims and the drawing whichis a flow diagram illustrating removal and recovery of carbon monoxidefrom a mixed feed stream.

In accordance with the present invention there is provided a carbonmonoxide absorbent consisting essentially of an inert diluent and atleast one copper (I) salt of an organic sulfonic acid or of a dialkylphosphate, as hereinafter described.

Further in accordance with this invention, there is provided a processfor the removal of carbon monoxide from a gas mixture containing samewhich comprises contacting such gas mixture in contacting zone with anabsorbent consisting essentially of an inert diluent and at least onecopper (I) salt of an organic sulfonic acid or of a dialkyl phosphate,as hereinafter described. Optionally, the carbon monoxide can beseparated in a separating zone from the thus-formed absorbent carbonmonoxide complex, and separately recovered.

The process of this invention is applicable to a variety of gasmixtures. The process can be used to remove carbon monoxide from towngas. The presence of a large amount of carbon monoxide in town gas makesit highly toxic to humans; for this reason, it is desirable to reducethe carbon monoxide content substantially. In making industrial gases,such as synthesis gas, carbon monoxide is generally produced as aco-product with hydrogen. However, many hydrogen-treating processes usemetal catalysts that are poisoned by the presence of carbon monoxide.Therefore, it is necessary to purify the hydrogen by removing the carbonmonoxide to prevent the poisoning of the catalysts. Such processesinclude ammonia synthesis and hydrorefining. In other processes, theindustrial gases are utilized primarily for the carbon monoxide therein.Such processes include phosgene and acrylate synthesis, methanation andthe like.

Of particular interest is the separation and concentration of carbonmonoxide from a gaseous stream resulting from the oxidative gasificationof coal or other carbonaceous material with a limited supply of oxygen.When air is used as the source of oxygen, the major separation isbetween carbon monoxide and nitrogen after the reaction water iscondensed and the acid gases, i.e., carbon dioxide and hydrogen sulfide,are removed by conventional means using commercially availableabsorbents for this purpose. For example, the acid gases can be removedby scrubbing in a hot potassium carbonate solution or in solutions ofmono- or diethanolamine. Any remaining sulfide can be removed by passingthe scrubbed gas through fixed beds of hot alkalized iron or hot zincoxide. Minor amounts of carbon dioxide remaining can be tolerated sincethis material is one of the products formed if the carbon monoxide issubsequently reacted with water over a supported nickel catalyst, forinstance, to form methane and carbon dioxide as a step in the formationof synthetic natural gas.

The copper (I) salts employed in the present invention are selected fromthe group consisting of:

(a) the copper (I) salt of an alkane sulfonic acid having from 4 to 20carbon atoms per molecule;

(b) the copper (I) salt of an aromatic sulfonic acid includinghydroxyaromatic and haloaromatic sulfonic acids having from 6 to 22carbon atoms per molecule;

(c) the copper (I) salt of a petroleum sulfonic acid; and

(d) the copper (I) salt of a dialkyl phosphate having from 1 to 12carbon atoms per alkyl member.

The alkane sulfonic acids useful in the practice of this invention canbe straight chain or branched. Examples of suitable alkane sulfonicacids include n-butanesulfonic acid, 2-ethylhexanesulfonic acid,2-methylnonanesulfonic acid, dodecanesulfonic acid,2-ethyl-5-n-octyldecanesulfonic acid, n-eicosanesulfonic acid and thelike. A presently preferred alkane sulfonic acid is2-ethyl-1-hexanesulfonic acid.

The aromatic, hydroxyaromatic and haloaromatic sulfonic acids useful inthe practice of this invention include benzenesulfonic acid,alkylbenzenesulfonic acids wherein the alkyl member contains from 1 to16 carbon atoms, such as p-toluenesulfonic acid,p-dodecylbenzenesulfonic acid, p-hexadecylbenzenesulfonic acid, and thelike, naphthalenesulfonic acids, phenolsulfonic acid, naphtholsulfonicacids and halo-benzenesulfonic acids, such as p-chlorobenzenesulfonicacid, p-bromobenzenesulfonic acid, and the like. A presently preferredaromatic sulfonic acid is p-dodecylbenzenesulfonic acid. Commerciallyavailable mixtures of o-, m- and p-dodecylbenzenesulfonic acid can beemployed. Preferably, the mixture employed is predominately, i.e. 85-90mole percent, the para isomer.

The petroleum sulfonic acids useful in the practice of this inventioncan be prepared from a deasphalted, solvent refined petroleum fractionhaving a viscosity of about 140 to about 720 SUS at 210° F. (99° C.). Apresently preferred sulfonation stock is a propane-fractionated, solventextracted dewaxed Mid-Continent oil of about 200 to 230 SUS at 210° F.(99° C.) and having a viscosity index of about 90 to 100, or higher. AMid-Continent oil is more precisely defined as a mixed base orintermediate base oil in "The Science of Petroleum", volume 1, page 7,Oxford University Press, London, New York and Toronto, 1938. Such oilis, for example, sulfonated with a 10 percent SO₃ -90 percent SO₂mixture in a continuous operation substantially as described in U.S.Pat. No. 3,135,693 to Whitney et al, using an SO₃ to oil weight ratio ofabout 0.08 and a reaction temperature of about 115° F. (46° C.). Thetotal reaction time is about 5 minutes, including the mixing and soakingperiods. The system is maintained in the liquid phase at a pressure of100-120 psig (689-827 kPa gage). Effluent from the reaction unit issubjected to a two-stage flash for SO₃ -SO₂ removal.

The dialkyl phosphates useful in the practice of this invention includedimethyl phosphate, diethyl phosphate, di-n-butyl phosphate,di-2-ethylhexyl phosphate, di-n-dodecyl phosphate and the like.

The absorbent compositions of the present invention are prepared byrefluxing a solution of the sulfonic acid or dialkyl phosphate in aninert diluent, as hereinafter described, together with cuprous oxide,with provision for removing the water of reaction, such as a Dean-Starktrap. The preparation is carried out in an oxygen-free inert atmosphere,such as under nitrogen. The molar ratio of acid to copper is about 1.The preparation is carried out for a time sufficient to producesubstantially complete reaction. The copper (I) salts can, if desired,be separated from the diluent by removing the diluent as by vacuumdistillation.

The diluents useful in the present invention include normally liquidsaturated aliphatic, saturated cycloaliphatic or aromatic hydrocarbons,preferably boiling in the approximate range of 60° to 150° C., such asn-hexane, n-octane, cyclohexane, benzene, toluene, the xylenes,ethylbenzene, and the like; halogenated hydrocarbons such as chloroformand chlorobenzene; ethylene glycol ethers such as ethylene glycolmonoethyl ether; and tetramethylene sulfone. Presently preferreddiluents are toluene and the xylenes. Mixtures of the above can also beemployed as diluents.

It is desirable to have as much of the copper (I) salt in the absorbentsystem as possible; the higher the salt/diluent ratio, the greater willbe the complexing capacity of the system, and the greater the amount ofcarbon monoxide that can be complexed. Broadly, the amount of the copper(I) salt in the diluent will be an effective amount, i.e., an amountsufficient to complex at least a portion of the carbon monoxide in thegas mixture to be treated. In general, the amount of the copper (I) saltcan range from 0.1 to 2 moles per liter of diluent. Salt/diluentmolarities of at least 0.5 mole of salt per liter of diluent have givenhighly satisfactory results. However, at a nominal molarity of about 2or more, the solution viscosity can increase enough to cause pumpingdifficulties, and such viscous solutions are preferably avoided.

The temperature at which the carbon monoxide is absorbed by theabsorbent system is not critical. The absorption can be carried out at atemperature in the approximate range of 0° C. to about 10° C. below theboiling point of the diluent. It is presently preferred to carry out theabsorption step at a temperature in the approximate range of 20° C. toabout 25° C. below the boiling point of the diluent.

The absorption step can be carried out at subatmospheric, atmospheric orsuperatmospheric pressures. Carbon monoxide partial pressures between0.1 and 20 atmospheres can be employed, preferably between 1 and 10atmospheres. The particular partial pressure employed will generally begoverned to some extent by the pressure at which the gaseous feed issupplied.

Once the absorption step has been completed, the carbonmonoxide/-absorbent complex is passed to a desorption means wherein thecarbon monoxide is liberated by heating the mixture to a temperature inthe approximate range of 10° C. below the boiling point of the diluentto the boiling point of the diluent. It is presently preferred that thedesorption step be carried out at the boiling point of the diluent.

The desorption step can be carried out at subatmospheric, atmospheric orsuperatmospheric pressures. Absolute pressures in the approximate rangeof 0.1 to 3 atmospheres, preferably from 0.5 to 2 atmospheres, can beemployed.

Referring now to the drawing, a feed stream containing carbon monoxideis fed by way of conduit 2 to an absorbing means 4, wherein the feedstream is contacted with the absorbent of the present invention. Theabsorbing means 4 can be of the conventional bubble tray type, a packedcolumn or any other liquid-gas contacting apparatus. Prior tointroduction of the feed into the absorbing means, the feed can bepassed into a guard chamber (not shown) which will serve to removematerials that can interfere with the main absorption process, i.e.,water, oxygen and hydrogen sulfide. Accordingly, the guard chamber cancontain an absorbent material different from that present in theabsorbing zone 4.

Line 6 at the top of the absorption zone 4 permits removal of the gas ofreduced carbon monoxide content. Line 8 at the bottom of the absorptionzone 4 conducts the carbon monoxide-enriched absorbent out of theabsorbing zone 4, through heat exchanger 10 to the desorption zone 12.

In the desorption zone 12, the carbon monoxide-enriched absorbent isheated to liberate the carbon monoxide which is withdrawn from the topof zone 12 through line 14. The thus-regenerated absorbent is withdrawnfrom the bottom of the desorption zone 12 through line 16, passedthrough heat exchanger 10 where it transfers some of its heat to thematerial in line 8, and is then returned to absorber zone 4. A portionof the absorbent in line 16 is passed through reboiler 17.

The carbon monoxide in line 14 can contain a small amount of gaseousdiluent. This material is passed through a heat exchanger 18 to cool thecombined gaseous stream to condense the diluent, thence into a firstseparating zone 20 wherein the carbon monoxide is separated from the nowliquid diluent. Carbon monoxide is withdrawn from the separating zone 20through line 22. The diluent is withdrawn from the separating zone 20through line 24 and returned to the desorbing zone 12 through line 26.The absorbent in the system is replenished, as necessary, through line27.

In one embodiment of this invention the feed stream consists essentiallyof carbon monoxide and nitrogen. Such a feed stream results from theoxidative gasification of a carbonaceous material, such as coal, whenair is used as the source of oxygen. The separated nitrogen withdrawnfrom absorbing zone 4 through line 6 is passed to expansion motor 28. Asthe nitrogen passes through the absorbing zone 4, it can carry over asmall amount of diluent, in the gaseous form. The diluent/nitrogen gasesin line 6 are expanded in turbo or reciprocating expansion motor 28under substantially adiabatic conditions. The resultant gas mixture mustbe at a temperature and pressure which will cause the diluentsubstantially to condense. The resultant cold gas mixture flows throughline 30 to separator 32 where an overhead nitrogen stream is removedthrough line 34 and a liquid diluent stream is removed through line 36.The liquid diluent in line 36 can be passed to desorption zone 12through line 26.

The expander motor 28 can provide mechanical energy or it can beconnected to an electrical generator 38 to provide electrical energy.

The carbon monoxide in line 22 can be compressed in turbo orreciprocating compressor 40. The compressed carbon monoxide in line 42can be passed through heat exchanger 44 which can be cooled by the coolnitrogen in line 34.

The compressor 40 is driven by motor 46. At least a portion of theenergy requirement of motor 46 can be provided by the generator 38.

The compressed, cooled carbon monoxide exiting from heat exchanger 44 ispassed through a separator 48 to remove any diluent that may have beencondensed in the compressor 40 and/or cooler 44. The carbon monoxide iswithdrawn from separator 48 through line 50. The separated diluent iswithdrawn through line 52 and passed to line 26 to be returned to thedesorber zone 12.

An advantage of the present invention is that the carbon monoxideabsorptive capacity of the copper (I) compounds of this invention arenot markedly influenced by temperature, up to the temperature at whichthe carbon monoxide begins to desorb. Hence, the absorber unit can beoperated at a temperature slightly below the desorption temperature ofcarbon monoxide and the desorber unit can be operated at or somewhatabove such temperature. Thus, the energy requirements for separating andrecovering carbon monoxide according to this invention are reduced.

Another advantage of the present invention is the relatively lowcorrosion rate of the copper (I) compounds of this invention. Forexample, corrosion studies conducted at the boiling point of copper (I)dodecylbenzene sulfonate in toluene at a nominal molarity of 0.9 showeda corrosion rate, in mils per year, of 62.6 for carbon steel, 4.4 for410 stainless steel and negligible for 304 stainless steel.

A further advantage of the present invention is that the copper (I)compounds of this invention can be easily regenerated should they bedeactivated by water or oxygen. Should the copper (I) compound behydrolyzed to cuprous oxide and the free acid, the reaction can bereversed by distilling off the water. Should the copper (I) compound beoxidized by oxygen to the copper (II) compound, the latter compound canbe reduced with hydrogen to form the copper (I) compound.

The following examples illustrate the invention:

EXAMPLE I

A number of copper (I) compounds were prepared by boiling a solution ofthe corresponding sulfonic acid or phosphate in the chosen solventtogether with cuprous oxide, under reflux with provision for removingthe water of reaction. A nitrogen purge was used throughout eachpreparation to exclude oxygen. The molar ratio of acid to copper in eachpreparation was about 1.

These various copper (I) compounds were tested for carbon monoxideabsorption. The results are shown in Table I below:

                                      Table I                                     __________________________________________________________________________    Carbon Monoxide Absorption in Various Cu(I) Compounds                                                                Vol. CO                                                             Absorption                                                                              (STP)/  Gm-Moles                                                                              Relative Rate          Cu(I) Compound                                                                          Diluent                                                                              Solubility.sup.(1)                                                                  Molarity.sup.(2)                                                                    Temperature (° C)                                                                Vol. Absorbent                                                                        Gm-Atom Cu                                                                            of                     __________________________________________________________________________                                                           Absorption             Copper(I) dodecyl-                                                                      Toluene                                                                              So    1     25        15.9    0.71    Very fast              benzenesulfonate                                                              Copper(I) 2-ethyl-                                                                      Toluene                                                                              So    1     25        14.3    0.64    Very fast              1-hexanesulfonate                                                             Copper(I) phenol-                                                                       Sulfolane                                                                            So    1     25        9.0     0.48    Fast at first,         sulfonate                                              then slow              Copper(I) toluene-                                                                      Toluene                                                                              Sl    0.5   25        3.5     0.31    Moderately fast        sulfonate                                                                     Copper(I) 1-hy-                                                                         Toluene                                                                              I     1     25        0       0       --                     droxypropane-                                                                 3-sulfonate                                                                   Copper(I) naphtha-                                                                      Cellosolve                                                                           Sl    1     25        8.5     0.38    Slow                   lenesulfonate                                                                 Copper(I) p-chloro-                                                                     Chloroform+                                                                          Sl    1     25        5.4     0.24    Very slow              benzenesulfonate                                                                        Toluene                                                             Copper(I) 1-amino-                                                                      Water  Sl    0.5   25        0       0       --                     2-naphthal-4-                                                                 sulfonate                                                                     Copper(I) p-amino                                                                       Water  D     0.5   25        0       0       --                     benzenesulfonate                                                              Copper Fatty                                                                            Water  D     0.5   25        0       0       --                     alcohol sulfate                                                               Copper(I) bis(2-                                                                        n-Octane                                                                             So    0.5   25        1.4     0.122   Moderately fast        ethylhexyl)                                            at first,              phosphate                                              then slow              Copper(I) butane-                                                                       p-Xylene                                                                             Sl    1.0   25        9.4     0.42    Very slow              sulfonate                                                                     Copper(I) pentane-                                                                      p-Xylene                                                                             Sl    0.5   25        7.2     0.65    Very slow              sulfonate                                                                     Copper(I) hexane-                                                                       p-Xylene                                                                             Sl    0.366 25        4.3     0.53    Very slow              sulfonate                                                                     Copper(I) heptane-                                                                      p-Xylene                                                                             Sl    0.48  25        7.2     0.67    Very slow              sulfonate                                                                     __________________________________________________________________________     .sup.(1) Indicates solubility of the copper(I) compound in the diluent        shown, according to the following key: So -- soluble; Sl -- slurry; D --      the Cu(I) compound disproportionated into copper and Cu(II) salt of the       organic cpd.                                                                  .sup.(2) Nominal molarity of the Cu(I) compound in the diluent in moles o     compound per liter of diluent.                                           

Inspection of the results shows best absorption is obtained when thecopper compound is completely soluble in the solvent. This is based ongram-moles carbon monoxide absorbed per gram-atom copper in the coppercompound and the faster rate of absorption. The data show the bestcopper compounds to be those prepared from dodecylbenzenesulfonic acidand 2-ethyl-1-hexanesulfonic acid. The most preferred copper compound iscopper(I) dodecylbenzenesulfonate in view of the results obtained and ofthe ready availability of the sulfonic acid.

EXAMPLE II

The ratio of cuprous oxide and dodecylbenzenesulfonic acid was varied inseveral preparations to determine what effect it and the concentrationof the resulting copper(I) compound had on absorption capacity. Thecompounds were prepared in the manner of Example I using toluene orp-xylene as the solvent. The results are presented in Table II.

                                      Table II                                    __________________________________________________________________________    Factors Affecting Preparation of                                              Copper(I) Dodecylbenzenesulfonate                                                                  CO Absorption                                                    Nominal                                                                             Acid/Copper                                                                          STP Vol./                                                                             gm-Mole CO                                       Run                                                                              Solvent                                                                            Molarity.sup.(1)                                                                    Ratio.sup.(1)                                                                        Vol. Absorbent                                                                        gm-Atom Cu.sup.(1)                               __________________________________________________________________________    1  Toluene                                                                            0.5   1.25    8.1    0.72                                             2  "    0.5   1.53    9.0    0.81                                             3  "    0.5   2.0     8.8    0.79                                             4  "     0.835                                                                              1.0    10.1    0.54                                             5  "    1.0   1.23   15.9    0.71                                             6  "    1.0   1.50   15.4    0.69                                             7.sup.(2)                                                                        "    1.0   1.02   20.2    0.90.sup.(3)                                     8  p-Xylene                                                                           1.0   1.01   19.3    0.86.sup.(3)                                     __________________________________________________________________________     .sup.(1) Based on amount of Cu.sub.2 O charged at the start of the            preparation.                                                                  .sup.(2) Fresh, laboratory-prepared Cu.sub.2 O was used in this               preparation. Commercially obtained Cu.sub.2 O was used in all other cases     .sup.(3) When allowance is made for the small amount of unreacted Cu.sub.     O remaining in the preparation flask the ratio of CO/Cu.sup.+ closely         approaches 1.                                                            

The data show it is preferable to use an acid/copper ratio of about 1 inpreparing the copper compound as runs 5-8 most clearly demonstrate. Asthe copper concentration in the diluent increases the amount of carbonmonoxide absorbed also increases. When the nominal molarity of thecopper is about 1, which is preferred because the resulting solutionviscosity is easily handled in a cyclic absorption-desorption process,the ratio of absorption of gram-moles carbon monoxide per gram-atomcopper is estimated to approach unity.

The effectiveness of copper(I) dodecylbenzenesulfonate to segregatecarbon monoxide from nitrogen is shown in this calculated example.

Referring to the drawing, a mixture of 95.1 mole percent nitrogen and4.9 mole percent carbon monoxide, representing a combustion gaspreviously stripped of water, hydrogen sulfide and carbon dioxide, ispassed to absorber tower 4 through line 2 at 280,000 cu. ft./hr. (7727m³ /hr) (2.07 MPa). The tower 4 has 15 trays and has a diameter of 48inches (1.2 m).

5,400 Gal./hr. (20.44 m³ /hr) of the copper(I) dodecylbenzenesulfonateabsorbent as a 0.9 molar solution in p-xylene are introduced to tower 4through conduit 16 at a temperature of about 165° F. (74° C.). The gasesare contacted within tower 4 with the absorbent solution. It is assumedthat the absorbent solution, at saturation conditions, absorbs 19 volumeof carbon monoxide per volume of absorbent solution at a temperature of165° F. (74° C.).

Nitrogen, containing 0.5 ppm CO, is withdrawn from the absorber tower 4through conduit 6 at a rate of 266,280 cu. ft./hr. (7538 m³ /hr).

The CO-saturated absorbent solution is withdrawn from tower 4 throughline 8, passed through heat exchanger 10 and thence to the desorbingtower 12. The tower 12 has 15 trays and has a diameter of 48 inches (1.2m). The liquid contents of tower 23 are heated to a temperature of 231°F. (110° C.). For this purpose, steam is supplied to the reboiler at1372 lbs./hr. (622 kg/hr). Carbon monoxide is withdrawn from thedesorbing tower 12 through line 14 at 13,720 cu. ft./hr. (622 m³ /hr).The regenerated absorbent solution is withdrawn from tower 12 throughline 16, passed through the heat exchanger 10 and then through a cooler,not shown, before being returned to the absorbing tower 4.

Reasonable variations and modifications, which will be apparent to thoseskilled in the art, can be made in this invention without departing fromthe spirit and scope thereof.

What is claimed is:
 1. A composition of matter suitable for theabsorption of carbon monoxide from a gas mixture containing same whichconsists essentially of a normally liquid hydrocarbon diluent having aboiling point in the approximate range of 60° to 150° C and at least onecopper(I) salt selected from the group consisting of(a) the copper(I)salt of an alkane sulfonic acid having from 4 to 20 carbon atoms permolecule; (b) an aromatic sulfonic acid having from 6 to 22 carbon atomsper molecule; (c) the copper(I) salt of a petroleum sulfonate acid; and(d) the copper(I) salt of a dialkyl phosphoric acid having from 1 to 12carbon atoms per alkyl member; wherein said copper(I) salt is present insaid diluent in an amount ranging from 0.1 to 2 moles per liter of saiddiluent.
 2. The composition of claim 1 wherein said diluent is selectedfrom the group consisting of saturated aliphatic, saturatedcycloaliphatic and aromatic hydrocarbons.
 3. The composition of claim 2wherein said salt is the copper(I) salt of p-dodecylbenzenesulfonicacid.
 4. The composition of claim 2 wherein said salt is the copper(I)salt of 2-ethyl-1-hexanesulfonic acid.
 5. The composition of claim 2wherein said diluent is toluene.
 6. A process for the preparation of acarbon monoxide absorbent consisting essentially of a normally liquidhydrocarbon diluent having a boiling point in the range of 60°-150° Cand an amount effective to complex carbon monoxide of at least onecopper(I) salt of a compound selected from the group consisting of:(a)an alkanesulfonic acid having from 4 to 20 carbon atoms per molecule;(b) an aromatic sulfonic acid having from 6 to 22 carbon atoms permolecule; (c) a petroleum sulfonic acid; and (d) a dialkyl phosphatehaving from 1 to 12 carbon atoms per alkyl member which comprisesadmixing said sulfonic acid or said dialkyl phosphate with copper(I)oxide in said diluent and heating the resulting mixture to remove thewater of reaction, said process being carried out in an inert atmospherefor a time sufficient to produce substantially complete reaction andthereafter recovering said copper(I) salt in said diluent as the productof the process.
 7. The process of claim 6 wherein said compound is2-ethyl-1-hexanesulfonic acid.
 8. The process of claim 6 wherein saidcompound is p-dodecylbenzene-sulfonic acid.
 9. The process of claim 6wherein said diluent is toluene.
 10. The process of claim 6 wherein saidcopper(I) oxide and said sulfonic acid or said dialkyl phosphate areadmixed in a molar ratio of about
 1. 11. The process of claim 6 whereinthe resulting absorbent contains said copper(I) salt in an amountranging from 0.1 to 2 moles per liter of said diluent.
 12. The processof claim 6 wherein said diluent is selected from the group consisting ofsaturated aliphatic, saturated cycloaliphatic and aromatic hydrocarbons.